Epothilones are macrolide compounds that find utility in the pharmaceutical field. For example, epothilones A and B having the structures:
have been found to exert microtubule-stabilizing effects similar to paclitaxel (TAXOL®) and hence cytotoxic activity against rapidly proliferating cells, such as, tumor cells or other hyperproliferative cellular disease, see Bollag et al., Cancer Res., Vol. 55, No. 11, 2325-2333 (1995).
Epothilones A and B are natural anticancer agents produced by Sorangium cellulosum that were first isolated and characterized by Hofle et al., DE 4138042; WO 93/10121; Angew. Chem. Int. Ed. Engl. Vol. 35, No13/14, 1567-1569 (1996); and J. Antibiot., Vol. 49, No. 6, 560-563 (1996). Subsequently, the total syntheses of epothilones A and B have been published by Balog et al., Angew. Chem. Int. Ed. Engl., Vol. 35, No. 23/24, 2801-2803, 1996; Meng et al., J. Am. Chem. Soc., Vol. 119, No. 42, 10073-10092 (1997); Nicolaou et al., J. Am. Chem. Soc., Vol. 119, No. 34, 7974-7991 (1997); Schinzer et al., Angew. Chem. Int. Ed. Eng., Vol. 36, No. 5, 523-524 (1997); and Yang et al., Angew. Chem. Int. Ed. Engl., Vol. 36, No. 1/2, 166-168, 1997. PCT WO98/25929 disclosed the methods for chemical synthesis of epothilone A, epothilone B, analogs of epothilone and libraries of epothilone analogs. The structure and production from Sorangium cellulosum DSM 6773 of epothilones C, D, E, and F was disclosed in WO98/22461.